Geosciences

DISCUSSION: Have you ever taken a vacation to a city and then drove by a rural area for a pit stop? Have you stopped and thought, “man it sure is cooler here than in the city?”

There’s a name for this feeling. It’s called the Urban Heat Island. In simpler terms, it says that cities are 1-5°C warmer than rural areas. The effects of this phenomenon can go beyond city limits. These are the reasons for the Urban Heat Island: reduction in evapotranspiration, composition of materials in the city, pollution, and excess heat from human (anthropogenic) activity.

By definition, evapotranspiration is when water gets transferred to the atmosphere by evaporation from the land and transpiration from plants. Unless there is a garden or park within city limits, there is reduced vegetation in the city. Therefore, this allows for more sensible heat and warmer temperatures. In addition to this, areas where water can’t be absorbed within the city promote runoff.

Urban areas have lower albedos, which means less reflection and more absorption of sunlight. The construction materials have high heat capacities and thermal conductivity. These are defined, respectfully as, the ability to raise a degree of an object by 1 degree Celsius, and the ability to conduct heat. Energy is stored in the day and released at night.

Pollution can act like a shield over the city. What is meant by this “shield of pollution” is that this “shield” can act as a barrier against outgoing longwave radiation from leaving. Once this radiation attempts to leave, the “shield” will just send it right back to the city. This explains the increase in nocturnal temperature in cities.

The following things humans do can release heat: transportation, cooling apparatuses such as air conditioners, street lights, etc.

In conclusion, the effects of urbanization can have an immediate effect on the weather.

DISCUSSION: For the island of Bali in Indonesia, a maximum level 4 alert has been issued on the volcanic alert system. Mount Agung (pictured) had been spewing ash for about a week with increasing intensity, but heightened seismic activity has Indonesia’s disaster mitigation agency raising the urgency to those who live in the designated exclusion zone to evacuate as soon as possible. This danger area, about an 8 to 10 kilometer radius around the volcano, is in a prime spot for a major eruption. So far only 40,000 people have fled, but 60,000 are still waiting to leave. According to the governor of Bali, an additional 150,000 people may be called on to evacuate.

Currently 445 flights to and from Indonesia’s top tourist destination have been canceled, stranding about 59,000 unfortunate travelers.

DISCUSSION: Vanuatu, a nation of islands located in the Pacific Ring of Fire (between Australia and Hawaii), is home to about 280,000 people and stretches nearly 800 miles. Ranked as the country most at risk for natural disasters in the world, recent volcanic activity has now added to Vanuatu’s reputation. On the island of Ambae, recent activity from the Monaro volcano has forced the entire population of the island of approximately 11,000 to evacuate. Most of those who evacuated are being transported by boat or are airlifted to one of the other nearly 80 islands in the island chain.

With rocks and gas spewing from the volcano, the government has issued the second-highest alert possible in their volcanic alert system for the first time ever at Level 4 (Level 5 indicates an eruption is imminent). Although they can measure seismic activity, it is impossible to predict exactly when an eruption will occur.

In addition, evacuations have been underway on the island of Bali in Indonesia. Mount Agung (in photo), a volcano located in the northeast region of the island, has been at its highest alert level for about a week. Nearly 134,000 people have been strongly urged to leave their homes. When the volcano last erupted in 1963, lava traveled 4.7 miles, ash was hurled up 12 miles, and about 1,100 people lost their lives.

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DISCUSSION: Within the past week, there have been definitive signs of activity in association with Mount Etna. As seen in the video above (courtesy of the Protezione Civile), there was a fairly large ash cloud emanating from close to the peak of Mount Etna (which is an active stratovolcano located on the east coast of Sicily, Italy, in the Metropolitan City of Catania, between the cities of Messina and Catania). As this eruption period continued through the course of the day back on February 28th, there were also other growing concerns. As a volcanic eruption occurs, there are often major concerns for a growing threat to commercial and private aviation interests.

This is due to the fact that as a volcanic eruption persists, increasingly larger amounts of volcanic ash are suspended into the localized atmosphere before spreading out from the point of origin (i.e., Mount Etna in this particular case) and affecting other geographic regions in and around the point source of the volcanic ash. This spreading out of the original volcanic ash plume occurs as the prevailing winds through the depth of the atmosphere transport the ash cloud in a given direction before being spread out in a more dispersed manner as the concentration of the ash cloud slowly decreases. Therefore, even after several days from the original eruption, any residual ash suspended in the atmosphere has the ability to damage aircraft engines along with ash ejected from any residual volcanic activity associated with Mount Etna.

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